Anoctamin 10/TMEM16K mediates convergent extension and tubulogenesis during notochord formation in the early chordate Ciona intestinalis.

During embryonic development, cells are organized into complex tissues and organs. A highly conserved organ shape across metazoans is the epithelial tube. Tube morphogenesis is a complex multistep process where the molecular mechanisms underlying the diversity of cell behaviors such as convergent extension, cell elongation, and lumen formation are still intensely studied. Here, using genome editing and quantitative imaging in the early chordate Ciona intestinalis we show that Ano10/Tmem16k, a member of the evolutionarily ancient family of transmembrane proteins called Anoctamin/TMEM16 is required for convergent extension, lumen expansion and connection during notochord morphogenesis. In addition, we find that loss of Cii.Ano10/Tmem16k hampers cell behavior and cytoskeletal organization during tubulogenesis. In vivo Ca2+ imaging revealed that genetic ablation of Cii.Ano10/Tmem16k hinders the ability of notochord cells to regulate bioelectrical signaling. Finally, we use electrophysiological recordings and a scramblase assay in tissue culture to demonstrate that Cii.Ano10/Tmem16k likely acts as an ion channel but not as a phospholipid scramblase. More generally, this work provides insights into the pre-vertebrate functions of Anoctamins and raises the possibility that Anoctamin/Tmem16 family members have an evolutionarily conserved role in tube morphogenesis.